Oxidation Number Changes in Reactants and Products Steps: - Calculate N oxidation number in HNO₃: H (+1) + N (x) + 3O (-6) = 0, so x = +5. - Calculate N oxidation number in NO: N (y) + O (-2) = 0, so y = +2; change = +2 - (+5) = -3. - Calculate S oxidation number in SO₂: S (z) + 2O (-4) = 0, so z = +4. - Calculate S oxidation number in HSO₄⁻: H (+1) + S (w) + 4O (-8) = -1, so w = +6; change = +6 - (+4) = +2. The calculated changes (-3 for N, +2 for S) do not match any choice exactly. Why B is correct: - Not applicable; B shows -2 +2, but actual changes are -3 +2 per standard oxidation number rules. Why the others are wrong: - A: Shows +3 for S, but S change is +2 (each O contributes -2). - C: Shows -2 for N and +3 for S; mismatches both values. - D: Shows -1 for N, but N decreases by …